Rich: > I was going by AZ's description of, "Some of the film images were > made with very long exposures - up to 15 minutes!" Most of mine are > in the 2-5 minute range and have been as long as an hour or so. I > doubt the batteries would hold up for any exposures longer than that > and I haven't looked into powering externally. I doubt I would ever > want to make such lengthy exposures, I lack the patience plus I would > likely need some way to keep the lens clear of condensation. > I have a solution for the lens condensation :) a dozen 2 ohm 5 watt resistors soldered in series wrapped around the front end of the lens and powered by a small 12V sealed lead-acid battery will do the trick! For larger lenses (I read these are often a problem, often solved with very elaborate methods) a sheet of 2 or 3mm glass cut to size (round) can have those cheap rear window car demister kits attached and run from a car battery through a rheostat to control the temperature/power consumption http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=26029264687 - this can be fitted over the front of the lens using electrical tape to make a good seal. The strips have minimal (almost no) effect on the image quality. powering a camera externally is easy, but sitting there for 6 hours is something I do not do well, so for my outdoor leave-it-in-the-paddock-overnight 35mm camera I grabbed a cheap timer that beeps at the conclusion of the set time. Ripping the wires from the speaker I connected them through a 'normally closed' microswitch to a simple transistor circuit to operate a solenoid. I set this solenoid in a bracket arrangement I made to hold down a mechanical cable release, so when I fire the camera, I slip the solenoid rod to lock down the end of the cable release. When the timer goes off X hours later, the solenoid retracts releasing the cable release and it hits the mcoswitch cutting off further power to the solenoid to preserve battery life and my exposure is done :) I like streaky star trails :) truth be told.. I build these gadget things because I want to see if I can make these pictures. Once i've done it, the novelty wears off and the gadget goes to the back of the cupboard. I still have to do the middle-of-the-city-on-a-nice-sunny-day long exposure yet with a pile of polarizers and ND's on the front. I think that would be fun k
